This invention relates to binders for holding loose leaf pages, and in particular to an improved mechanism for opening and closing binders.
A ring binder retains loose leaf pages, such as hole-punched papers, in a file or notebook. It features ring members for retaining the papers which may be selectively opened to add or remove papers, or closed to retain papers while allowing them to be moved along the ring members. Levers are typically provided on both ends of the binder for moving the ring members between the open and closed positions.
One drawback to ring binders of the prior art is that when ring members are being closed, they snap shut with a strong magnitude of force which can cause injury. Further, many ring binders of the prior art have ring members which are not lockable in the closed position, thereby being vulnerable to inadvertently opening when heavily loaded with loose leaf papers. Also, the clamping force within each ring is not uniform with the clamping force in other rings, causing uneven movement and potentially resulting in gaps on closed rings.
Reference is made to the following co-assigned U.S. Patents for background regarding ring binder mechanisms:
Patent No.DateTitle5,354,142Oct. 11, 1994Ring Binder5,577,852Nov. 26, 1996Ring BinderMechanism5,755,513May 26, 1998Ring Binder5,842,807Dec. 1, 1998Ring Binder5,879,097Mar. 9, 1999Ring Binder6,033,144Mar. 7, 2000Ring BinderMechanism6,168,339Jan. 2, 2001Ring Binder